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1 Dorsal fins are found on the back of the fish. 2  There may be up to three of them. 3  The fish uses this fin for balance in the water and sudden movements. 4  Caudal fins are also known as tail fins.5  This is what we refer to as the fish's tail. 6  Anal fins are on the ventral (bottom) surface of the fish, behind the anus. Dorsal fins are found on the back of the fish. 2  There may be up to three of them. 3  The fish uses this fin for balance in the water and sudden movements. 4  Caudal fins are also known as tail fins.
Class Osteichthyes (the bony fish) is the largest class of vertebrates with over 20,000 species. The total numbers of fishes exceed that of all other kinds of vertebrates combined.obe-finned fish, the other type of bony fish, have muscular fins supported by bones. Only one species of lobe-finned fish, the coelacanth, still lives. Key features of Osteichthyes. 1  Skeleton more or less bony, vertebrae numerous. 2  Skin with mucous glands and embedded dermal scales. 3  some without scales. 4  Paired fins.